1. Field of the Invention
This invention relates generally to motor vehicles and, more particularly, to techniques for the reduction of drag by providing the motor vehicle with structure on the rear surface.
2. Description of the Related Art
In the related art, the use of structure associated with rear motor vehicle surfaces has been described. U.S. Pat. No. 4,702,509, issued on Oct. 27, 1987 to Elliott, Sr., describes, inter alia, an inflatable balloon bag member associated with a rear of a tractor-trailer which provides for a streamlining of the vehicle region. The collapsibility of the streamlining member permits convenient storage when access to the rear of the motor vehicle is required and at low vehicle speeds when the streamlining is no longer required. U.S. Pat. No. 4,180,290, issued on Dec. 25, 1979 to Drews, and U.S. Pat. No. 4,284,302, issued on Aug. 18, 1981 also to Drews, describe the use of wave shaped flutes on the surface of a generally streamlined motor vehicle, the flutes generally extending longitudinally at an angle to the direction of travel. The wave shaped flutes are located on the rear portion of the motor vehicle, a portion on which the streamline structure is continued in the described embodiment. U.S. Pat. No. 4,776,535, issued on Oct. 11, 1988 to Paterson et al.; U.S. Pat. No. 4,789,117, issued on Dec. 6, 1988 to Paterson et al; and U.S. Pat. No. 4,813,633 issued on Mar. 21, 1989 to Werle et al. describe a wave-like structure in the sides and top of the rear of a tractor-trailer and in the trailing edge of an airfoil which results in reduced drag. U.S. Pat. No. 2,800,291, issued on July 23, 1957 to Stephens, and U.S. Pat. No. 2,899,150, issued on Aug. 11, 1959 to Ellis, Jr., describe structure in an airfoil which prevents turbulence. U.S. Pat. No. 4,861,093, issued on Aug. 29, 1989 to Chapman, describes a structure in the rear surface of a motor vehicle which minimizes turbulence along the rear surface by permitting a flow of air "through" the rear surface. Russian Pat. No. 927,616 , issued May 15, 1982, and U.S. Pat. No. 4,682,808, issued on July 28, 1987 to Bilanin, describe the panel configurations suitable for mounting on the rear of a tractor-trailer which result in the reduction of drag. The flat panels can be positioned along the rear surface for convenient storage when not required.
The structures described by the foregoing references, those references which are applicable to tractor-trailers or other motor vehicles having a large and generally flat rear surface, are generally so large in extent that they must be stored when access to the interior of the motor vehicle is required. These structures also can provide and appreciable contribution to the overall length of the motor vehicle.
A need has therefore been felt for a structure associated with the rear surface of a motor vehicle, such as a van or tractor-trailer, which can provide drag reduction while still permitting convenient access to the interior of the vehicle and without requiring storage of the structure during such access.